CN103063643A - Ultrasensitive fluorescence response method for detecting melamine in milk - Google Patents

Ultrasensitive fluorescence response method for detecting melamine in milk Download PDF

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CN103063643A
CN103063643A CN2013100003965A CN201310000396A CN103063643A CN 103063643 A CN103063643 A CN 103063643A CN 2013100003965 A CN2013100003965 A CN 2013100003965A CN 201310000396 A CN201310000396 A CN 201310000396A CN 103063643 A CN103063643 A CN 103063643A
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aunps
melamine
moll
quantum dot
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孙春燕
曹先一
张民伟
李宏坤
郭佳佳
沈斐
罗叶丽
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Jilin University
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Jilin University
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Abstract

The invention relates to a method for detecting melamine in milk which is built based on the inner filter effect (IFE) between cysteine (L-Cys)-modified CdS quantum dots and citric acid ligand coating gold nanoparticles (AuNPs), and belongs to the field of analytical chemistry. The method comprises the detecting steps of preparing the AuNPs, synthesizing and purifying the L-Cys-modified CdS quantum dots, pre-treating a milk sample and detecting the melamine in the milk. According to the principle of recovering the fluorescence intensity of the CdS quantum dots by adopting the AuNPs to cause the fluorescence quenching of the CdS quantum dots and adopting the melamine to induce the aggregation of the AuNPs, the method can simply, quickly and sensitively detect the melamine in the milk so as to provide convenience to future dairy industry.

Description

A kind of hypersensitive, fluorescence response method detect melamine in the milk
Technical field
Utilize the special chemical constitution of melamine, fluorescence inner filtering effect (IFE) between the golden nanometer particle (AuNPs) that the CdS quantum dot of modifying based on halfcystine (L-Cys) and citric acid part coat and the detection method of melamine in the milk set up belongs to technical field of analytical chemistry.
Background technology
The chemical name of melamine (melamine) is 2,4,6-triamido-1,3,5-triazines, and its structural formula is as follows:
Figure BSA00000833539700011
It is a kind of important azacyclo-Organic Chemicals, main Material Used science.
Because its nitrogen content is up to 66.7%, so it is often added in food and the animal feed artificially to improve N content.
The low toxicity of melamine own, but melamine generates cyanuric acid under acidity or alkali condition, melamine and its concurrent cyanuric acid form insoluble crystallization by hydrogen bond in kidney, therefore form kidney stone, the long-term melamine of taking in high concentration can cause kidney failure even death, and is especially very large to children and teenager's harm.
In September, 2008, a plurality of provinces and cities such as Gansu, Jiangsu concentrate and baby's calculus event occurs, find that with " Invest, Then Investigate " infant has the history of edible Sanlu board baby formula milk powder more, investigate through relevant departments, find that there are serious quality problems in the Sanlu board baby formula milk powder that the said firm produces, Sanlu Group sends and recalls subsequently, claims that milk powder is subject to the pollution of melamine, and determines to recall immediately the Sanlu board baby milk powder of producing in the past on August 6th, 2008.Then, other brand milk powder of some domestic productions and part have in the food of dry milk component and have also detected successively melamine, cause the Credibility Crisis of Chinese Dairy Industry, also bring huge negative effect to daily life.
At present, the method for detection melamine mainly contains high performance liquid chromatography, gas chromatography tandem mass spectrometry, Liquid Chromatography-Tandem Mass Spectrometry method etc.These method detection limits are low, highly sensitive, but analytic process is tediously long, it is derivative to need, instrument is expensive and need professional operating personnel, can not be applied to field quick detection.
Chinese government regulation: the maximum maximum permission quantity of melamine in baby milk powder and other daily bread is respectively 1.0 and 2.5mg/kg.
Summary of the invention
The method that the purpose of this invention is to provide the IFE between the AuNPs that a kind of CdS quantum dot of modifying based on L-Cys and citric acid part coat and set up is used for detecting fast, simply, delicately the content of milk melamine.
Technical matters: utilize the special chemical constitution of melamine, fluorescence inner filtering effect (IFE) between the golden nanometer particle (AuNPs) that the CdS quantum dot of modifying based on halfcystine (L-Cys) and citric acid part coat, set up the detection method of melamine in a kind of milk, its Method And Principle is the fluorescent quenching that monodispersed AuNPs can cause the CdS quantum dot, in the situation that has melamine to exist, the amino of melamine is combined in the AuNPs surface by coordination, the absorption spectrum that causes AuNPs changes, the competitive reaction of melamine and AuNPs, recover the fluorescence intensity of CdS quantum dot, and then can detect by the variation of observe system fluorescence intensity the melamine in the milk.
Technical scheme of the present invention:
May further comprise the steps: the preparation of AuNPs; Synthetic and the purifying of the CdS quantum dot that L-Cys modifies; The spectral characterization of AuNPs and CdS quantum dot; The AuNPs transmission electron microscope characterizes; Variable concentrations AuNPs is to the effect of CdS quantum dot; The optimization of AuNPs concentration; The foundation of detection method; The disturbance material is to the interference experiment of system; Detect the melamine in the milk.
(1) preparation of AuNPs:
Glassware used in the experiment all soaks 24h with chloroazotic acid, and redistilled water cleans, dry for standby, and the used distilled water of reagent preparation need be by the membrane filtration of 0.45 μ m; During preparation, in there-necked flask, add the gold chloride 50mL of 1mmol/L, make its boiling in the situation that stir heating, the trisodium citrate 5mL that adds fast 38.8mmol/L, heat while stirring, solution is by the faint yellow claret that becomes, and reaction continues 10min, stopped heating, continue to stir 10min, after solution is cooled to room temperature, with the micro-pore-film filtration of 0.45 μ m, 4 ℃ of preservations, prepared AuNPs particle diameter is 13nm; The AuNPs that makes is stand-by with pure water dilution in 1: 4 by volume, and the concentration after the dilution is 1.4 * 10 -9Mol/L.
(2) the synthetic and purifying of the CdS quantum dot of L-Cys modification:
Weighing 0.01M CdCl at first 2Be dissolved in the 15mL deionized water, logical N 260min under the condition of magnetic agitation, adds 30mL 0.01M L-Cys aqueous solution again, adjusts its PH to 8.5-9 with 1M NaOH, continues logical N 2Then 60min slowly drips 15mL 0.01M Na 2S solution.Mixed solution naturally cools to room temperature and continues to stir 6h at 50 ℃ of heating 2h.The CdS quantum dot solution adds the isopropyl alcohol with volume, and centrifugal purification is multiple water-soluble after the vacuum drying.
(3) spectral characterization of AuNPs and CdS quantum dot:
Adopt UV-2550 ultraviolet-visible spectrophotometer (Japanese Shimadzu company) to measure respectively the ultraviolet-visible absorption spectroscopy of AuNPs and CdS quantum dot; Fluorescence spectrum when adopting RF-5301 fluorophotometer (Japanese Shimadzu company) to measure excitation wavelength to be 360nm.
(4) the AuNPs transmission electron microscope characterizes
AuNPs and AuNPs-melamine are dripped respectively on the copper mesh that is coated with carbon film, and after room temperature was dried, with TECNAI F20 its size of transmission electron microscope observing and pattern, accelerating potential was 200kV.
(5) variable concentrations AuNPs is to the effect of CdS quantum dot:
The AuNPs (a, the 0molL that in 12 test tubes (5.0mL), add successively first different amounts -1, b, 0.14 * 10 -9MolL -1, c, 0.28 * 10 -9MolL -1, d, 0.42 * 10 -9MolL -1, e, 0.56 * 10 -9MolL -1, f, 0.70 * 10 -9MolL -1, g, 0.84 * 10 -9MolL -1, h, 0.98 * 10 -9MolL -1, i, 1.12 * 10 -9MolL -1, j, 1.26 * 10 -9MolL -1, k, 1.40 * 10 -9MolL -1), add respectively again pure water and be settled to 2mL, make potpourri at 25 ℃ of lower reaction 10min, add at last 7.8 * 10 -7MolL -1CdS quantum dot 1mL, measure its fluorescence spectrum.
(6) optimization of AuNPs concentration:
Get 21 test tubes (5.0mL) and be divided into 3 groups, 7 every group; Add respectively the AuNPs of variable concentrations in 3 groups of test tubes, make its ultimate density be respectively 5.6 * 10 -10MolL -19.8 * 10 -10MolL -11.40 * 10 -9MolL -1. more successively to each the group 1.-
Figure BSA00000833539700021
Add the melamine of variable concentrations in number test tube, make it reach respectively certain ultimate density (a, 7 μ gL -1, b, 14 μ gL -1, c, 21 μ gL -1, d, 28 μ gL -1, e, 35 μ gL -1, f, 42 μ gL -1, g, 49 μ gL -1), make potpourri at 25 ℃ of lower reaction 10min, add at last CdS quantum dot 1mL, measure its fluorescence spectrum.
(7) foundation of detection method:
In 7 test tubes (5.0mL), add respectively first AuNPs, add successively again the melamine of variable concentrations, make it reach respectively certain ultimate density (a, 7 μ gL -1, b, 14 μ gL -1, c, 21 μ gL -1, d, 28 μ gL -1, e, 35 μ gL -1, f, 42 μ gL -1, g, 49 μ gL -1), make potpourri at 25 ℃ of lower reaction 10min, add at last CdS quantum dot 1mL, measure its fluorescence spectrum.
(8) the disturbance material is to the interference experiment of system:
Respectively different interfering materials is joined in the AuNPs-CdS system of the melamine that contains 35 μ g/L, by the described detection method of claim 8, measure fluorescence spectrum; The concentration of each interfering material is respectively Cobastab 1(0.44gL -1), glucose (30gL -1), threonine (143gL -1), K +(143gL -1), Na +(43gL -1), Cl -(141gL -1), NO 3 -(150gL -1), tryptophane (7.5gL -1), glycocoll (7.5gL -1), lysine (14gL -1), histidine (7.5gL -1), vitamin C (1gL -1), Mg 2+(1gL -1), Ca 2+(5.65gL -1), lactose (25gL -1), PO 4 3-(10gL -1).
(9) melamine in the detection milk:
The melamine of variable concentrations is joined in the milk, make melamine wherein reach respectively certain ultimate density (a, 50 μ gL -1, b, 100 μ gL -1, c, 150 μ gL -1, d, 200 μ gL -1, e, 250 μ gL -1, f, 300 μ gL -1, g, 350 μ gL -1); Then in the centrifuge tube of 10mL, in the milk of 0.5g, add respectively the chloroacetic acid of 3.75mL and the chloroform of 1.25mL, whirlpool concussion 1min, with protein precipitation, and the organism in the dissolved matrix, ultrasonic processing 15min then, the centrifugal 10min precipitation and separation of 12000rmp; The supernatant of 2mL is transferred in another centrifuge tube, used the Na of 1M 2CO 3Adjusting pH is 8.0, solution 10000rmp again centrifugal 10min remove precipitation; Supernatant filters with 0.45 μ m GTTP (polycarbonate leaching film), respectively gets 300 μ L final solutions, by the described detection method of claim 8, joins in the detection system, measures fluorescence spectrum separately.
Beneficial effect of the present invention: the present invention has prepared a kind of AuNPs of citric acid part coating and the CdS quantum dot that a kind of L-Cys modifies, and set up a kind of method that can detect quick, easy, sensitive, at low cost melamine in the milk, for the from now on supervision of dairy industry provides convenience.
Description of drawings
The ultraviolet-visible absorption spectroscopy of Fig. 1 a:AuNPs; The fluorescence spectrum of b:L-Cys-CdS quantum dot; The ultraviolet-visible absorption spectroscopy of c:L-Cys-CdS quantum dot.
Fig. 2 transmission electron microscope photo: (A) AuNPs; (B) AuNPs-melamine; Illustration is the AuNPs of scale when being 20nm among the A.
There is the fluorescence spectrum of lower CdS quantum dot in Fig. 3 variable concentrations AuNPs.AuNPs concentration is respectively 0,0.14,0.28,0.42,0.56,0.70,0.84,0.98,1.12,1.26and 1.40 * 10 among the a-k -9MolL -1CdS QDs, 7.8 * 10 -7MolL -1
The fluorescence response value of Fig. 4 CdS quantum dot in containing the AuNPs-melamine system of variable concentrations.AuNPs·：5.6×10 -10mol·L -1；■：9.8×10 -10mol·L -1；▲：1.40×10 -9mol·L -1。CdS?7.8×10 -7mol.L -1。
Fig. 5 variable concentrations melamine is on the impact of AuNPs-CdS system fluorescence intensity.Melamine concentration is respectively 7,14,21,28,35,42and, 49 μ gL among the a-g -1Cds QDs, 7.8 * 10 -7MolL -1AuNPs, 9.8 * 10 -10MolL -1
The fluorescence spectrum of system when Fig. 6 (A) disturbance material exists; (B) the disturbance material is on the impact of system.Interfering material: Cobastab 1(0.44gL -1), glucose (30gL -1), threonine (143gL -1), K +(143gL -1), Na +(43gL -1), Cl -(141gL -1), NO 3 -(150gL -1), tryptophane (7.5gL -1), glycocoll (7.5gL -1), lysine (14gL -1), histidine (7.5gL -1), vitamin C (1gL -1), Mg 2+(1gL -1), Ca 2+(5.65gL -1), lactose (25gL -1), PO 4 3-(10gL -1).Melamine: 35 μ g/L; Cds QDs, 7.8 * 10 -7MolL -1AuNPs, 9.8 * 10 -10MolL -1
The typical curve that Fig. 7 actual sample detects.Melamine concentration is respectively 50,100,150,200,250,300and, 350 μ gL among the a-g -1; Cds QDs, 7.8 * 10 -7MolL -1AuNPs, 9.8 * 10 -10MolL -1
Fig. 8 recovery testu.
Embodiment
The preparation of AuNPs
Material/agent: available from gold chloride and the trisodium citrate of Beijing Chemical Plant.
Method: glassware used in the experiment all soaks 24h with chloroazotic acid, and redistilled water cleans, dry for standby, and the used distilled water of reagent preparation need be by the membrane filtration of 0.45 μ m; During preparation, in there-necked flask, add the gold chloride 50mL of 1mmol/L, make its boiling in the situation that stir heating, the trisodium citrate 5mL that adds fast 38.8mmol/L, heat while stirring, solution is by the faint yellow claret that becomes, and reaction continues 10min, stopped heating, continue to stir 10min, after solution is cooled to room temperature, with the micro-pore-film filtration of 0.45 μ m, 4 ℃ of preservations, prepared AuNPs particle diameter is 13nm; The AuNPs that makes is stand-by with pure water dilution in 1: 4 by volume, and the concentration after the dilution is 1.4 * 10 -9Mol/L.
The result: characterize through transmission electron microscope, prepared gold nanometer particle grain size is 13nm, and favorable dispersibility, and particle diameter is even.
Synthetic and the purifying of the CdS quantum dot that L-Cys modifies
Material/agent: available from Na2S, L-Cys, the CdCl of Chemical Reagent Co., Ltd., Sinopharm Group 2NaOH available from the Beijing Chemical Plant.
Method: weighing 0.01M CdCl at first 2Be dissolved in the 15mL deionized water, logical N 260min under the condition of magnetic agitation, adds 30mL0.01M L-Cys aqueous solution, adjusts its pH to 8.5-9 with 1M NaOH, continues logical N 2Then 60min slowly drips 15mL 0.01M Na 2S solution.Mixed solution naturally cools to room temperature and continues to stir 6h at 50 ℃ of heating 2h.The CdS quantum dot solution adds the isopropyl alcohol with volume, and centrifugal purification is multiple water-soluble after the vacuum drying.
The result: the CdS quantum point grain diameter that prepared L-Cys modifies is 2.8nm, and concentration is 4.7 * 10 -6Mol/L, and favorable dispersibility, particle diameter is even.
Research variable concentrations AuNPs is on the impact of the fluorescence spectrum of CdS quantum dot
The golden nanometer particle of material/agent: 13nm; The CdS quantum dot.
Method: the AuNPs (Au0molL that in 11 test tubes (5.0mL), adds successively first different amounts -1, b, 0.14 * 10 -9MolL -1, c, 0.28 * 10 -9MolL -1, d, 0.42 * 10 -9MolL -1, e, 0.56 * 10 -9MolL -1, f, 0.70 * 10 -9MolL -1, g, 0.84 * 10 -9MolL -1, h, 0.98 * 10 -9MolL -1, i, 1.12 * 10 -9MolL -1, j, 1.26 * 10 -9MolL -1, k, 1.40 * 10 -9MolL -1), add respectively again pure water and be settled to 2mL, make potpourri at 25 ℃ of lower reaction 10min, add at last 7.8 * 10 -7The CdS quantum dot 1mL of mol/L measures its fluorescence spectrum.
The result: the AuNPs of variable concentrations can make the fluorescence generation quencher in various degree of CdS quantum dot.
The optimization of AuNPs concentration
The golden nanometer particle of material/agent: 13nm; The CdS quantum dot; Melamine solution.
Method: get 21 test tubes (5.0mL) and be divided into 3 groups, 7 every group; Add respectively the AuNPs of variable concentrations in 3 groups of test tubes, make its ultimate density be respectively 5.6 * 10 -10MolL -19.8 * 10 -10MolL -11.40 * 10 -9MolL -1. add successively again the melamine of variable concentrations in 7 test tubes of each group, make it reach respectively certain ultimate density (a, 7 μ gL -1, b, 14 μ gL -1, c, 21 μ gL -1, d, 28 μ gL -1, e, 35 μ gL -1, f, 42 μ gL -1, g, 49 μ gL -1), make potpourri at 25 ℃ of lower reaction 10min, add at last CdS quantum dot 1mL, measure its fluorescence spectrum.
The result: the result shows, the concentration of the suitableeest AuNPs is 9.8 * 10 -10MolL -1
The optimization in reaction time
The golden nanometer particle of material/agent: 13nm; Melamine solution.
Method: with 900 μ gL -1Melamine joins 9.8 * 10 -10MolL -1AuNPs solution in, scan its absorption spectrum every 30s.
The result: the result shows, optimum reacting time is 10min.
The optimization of pH
The golden nanometer particle of material/agent: 13nm; The CdS quantum dot; Melamine solution.
Method: add successively AuNPs, melamine and quantum dot in 8 test tubes (5.0mL), ultimate density is respectively 9.8 * 10 -10Mol/L, 35 μ g/L, 7.8 * 10 -7MolL -1HCl or NaOH with 0.1mol/L regulate pH from 4 to 11, measure its fluorescence spectrum.
The result: the result shows, best pH is 8.
The foundation of detection method
The golden nanometer particle of material/agent: 13nm; The CdS quantum dot; Melamine solution.
Method: in 7 test tubes (5.0mL), add respectively 9.8 * 10 first -10MolL -1AuNPs, add successively again the melamine of variable concentrations, make it reach respectively certain ultimate density (a, 7 μ gL -1, b, 14 μ gL -1, c, 21 μ gL -1, d, 28 μ gL -1, e, 35 μ gL -1, f, 42 μ gL -1, g, 49 μ gL -1), make potpourri at 25 ℃ of lower reaction 10min, add at last CdS quantum dot 1mL, measure its fluorescence spectrum.
The result: the melamine of variable concentrations can make the fluorescence generation recovery in various degree of AuNPs-CdS system, and the method can be used for the quantitative detection of melamine.
The disturbance material is to the interference experiment of system
The golden nanometer particle of material/agent: 13nm; The CdS quantum dot; Melamine solution.
Method: respectively different interfering materials is joined in the AuNPs-CdS system of the melamine that contains 35 μ g/L, by the described detection method of claim 8, measure fluorescence spectrum; The concentration of each interfering material is respectively Cobastab 1(0.44gL -1), glucose (30gL -1), threonine (143gL -1), K +(143gL -1), Na +(43gL -1), Cl -(141gL -1), NO 3 -(150gL -1), tryptophane (7.5gL -1), glycocoll (7.5gL -1), lysine (14gL -1), histidine (7.5gL -1), vitamin C (1gL -1), Mg 2+(1gL -1), Ca 2+(5.65gL -1), lactose (25gL -1), PO 4 3-(10gL -1).
The result: the interfering material that may exist in the milk on this detection method without impact.
The milk actual sample is detected.
The golden nanometer particle of material/agent: 13nm; The CdS quantum dot; Melamine solution; Chloroacetic acid, chloroform available from the Beijing Chemical Plant; The milk of buying on the local market.
Method: in the centrifuge tube of 10mL, in the milk of 0.5g, add respectively the chloroacetic acid of 3.75mL and the chloroform of 1.25mL, whirlpool concussion 1min, with protein precipitation, and the organism in the dissolved matrix, ultrasonic processing 15min then, the centrifugal 10min precipitation and separation of 12000rmp; The supernatant of 2mL is transferred in another centrifuge tube, used the Na of 1M 2CO 3Adjusting pH is 8.0, solution 10000rmp again centrifugal 10min remove precipitation; Supernatant filters with 0.45 μ m GTTP polycarbonate leaching film and obtains final solution, is used for detection method described in the claim 8; When joining a certain amount of melamine in the milk, also take identical pre-service and analytical procedure with aforementioned process.
The result: among the present invention, detecting of melamine is limited to 0.017mg/L, and the range of linearity is 0.05～0.35mg/L, and recovery of standard addition is (85.2～98.9) %.

Claims (10)

1. the fluorescence inner filtering effect (IFE) between the golden nanometer particle (AuNPs) that the CdS quantum dot of modifying based on halfcystine (L-Cys) and citric acid part coat, and utilize the special chemical constitution of melamine molecule, set up the detection method of melamine in a kind of milk, its characteristics are that monodispersed AuNPs can cause the fluorescent quenching of CdS quantum dot, and its amino is combined in the AuNPs surface by coordination when having melamine to exist, the absorption spectrum that can cause AuNPs changes, and then the fluorescence intensity of CdS quantum dot is restored, therefore can utilize the melamine in the above-mentioned principle detection milk, may further comprise the steps: the preparation of AuNPs; Synthetic and the purifying of the CdS quantum dot that L-Cys modifies; The spectral characterization of AuNPs and CdS quantum dot; The AuNPs transmission electron microscope characterizes; Variable concentrations AuNPs is to the effect of CdS quantum dot; The optimization of AuNPs concentration; The foundation of detection method; The disturbance material is to the interference experiment of system; Detect the melamine in the milk.
2. the method for claim 1, the preparation process of wherein said AuNPs is as follows:
Glassware used in the experiment all soaks 24h with chloroazotic acid, and redistilled water cleans, dry for standby, and the used distilled water of reagent preparation need be by the membrane filtration of 0.45 μ m; During preparation, in there-necked flask, add the gold chloride 50mL of 1mmol/L, make its boiling in the situation that stir heating, the trisodium citrate 5mL that adds fast 38.8mmol/L, heat while stirring, solution is by the faint yellow claret that becomes, and reaction continues 10min, stopped heating, continue to stir 10min, after solution is cooled to room temperature, with the micro-pore-film filtration of 0.45 μ m, 4 ℃ of preservations, prepared AuNPs particle diameter is 13nm; The AuNPs that makes is stand-by with pure water dilution in 1: 4 by volume, and the concentration after the dilution is 1.4 * 10 -9Mol/L.
3. the method for claim 1, the CdS quantum dot that wherein said L-Cys modifies synthetic as follows with purification step:
Weighing 0.01M CdCl at first 2Be dissolved in the 15mL deionized water, logical N 260min under the condition of magnetic agitation, adds 30mL 0.01ML-Cys aqueous solution again, and adjusting its pH with 1M NaOH is 8.5-9, continues logical N 2Then 60min slowly drips 15mL 0.01M Na 2S solution.Mixed solution naturally cools to room temperature and continues to stir 6h at 50 ℃ of heating 2h, and the CdS quantum dot solution adds the isopropyl alcohol with volume, and centrifugal purification is multiple water-soluble after the vacuum drying.
4. the method for claim 1, the spectral characterization step of wherein said AuNPs and CdS quantum dot is as follows:
Adopt UV-2550 ultraviolet-visible spectrophotometer (Japanese Shimadzu company) to measure respectively the ultraviolet-visible absorption spectroscopy of AuNPs and CdS quantum dot; Fluorescence spectrum when adopting RF-5301 fluorophotometer (Japanese Shimadzu company) to measure excitation wavelength to be 360nm.
5. the method for claim 1, the step that wherein said AuNPs transmission electron microscope characterizes is as follows:
AuNPs and AuNPs-melamine are dripped respectively on the copper mesh that is coated with carbon film, and after room temperature was dried, with TECNAI F20 its size of transmission electron microscope observing and pattern, accelerating potential was 200kV.
6. the method for claim 1, wherein said observation variable concentrations AuNPs is as follows to the step of the effect of CdS quantum dot:
The AuNPs (a, the 0molL that in 11 test tubes (5.0mL), add successively first different amounts -1B, 0.14 * 10 -9MolL -1C, 0.28 * 10 -9MolL -1D, 0.42 * 10 -9MolL -1E, 0.56 * 10 -9MolL -1F, 0.70 * 10 -9MolL -1G, 0.84 * 10 -9MolL -1H, 0.98 * 10 -9MolL -1I, 1.12 * 10 -9MolL -1J, 1.26 * 10 -9MolL -1K, 1.40 * 10 -9MolL -1), add respectively again pure water and be settled to 2mL, make potpourri at 25 ℃ of lower reaction 10min, add at last 7.8 * 10 -7MolL -1CdS quantum dot 1mL, measure its fluorescence spectrum.
7. the method for claim 1, the Optimization Steps of wherein said AuNPs concentration is as follows:
Get 21 test tubes (5.0mL) and be divided into 3 groups, 7 every group; Add respectively the AuNPs of variable concentrations in 3 groups of test tubes, make its ultimate density be respectively 5.6 * 10 -10MolL -19.8 * 10 -10MolL -11.40 * 10 -9MolL -1Add successively again the melamine of variable concentrations in 7 test tubes of each group, make it reach respectively certain ultimate density (a, 7 μ gL -1B, 14 μ gL -1C, 21 μ gL -1D, 28 μ gL -1E, 35 μ gL -1F, 42 μ gL -1G, 49 μ gL -1), make potpourri at 25 ℃ of lower reaction 10min, add at last 7.8 * 10 -7MolL -1CdS quantum dot 1mL, measure its fluorescence spectrum.
8. the method for claim 1, the step of the foundation of wherein said detection method is as follows:
In 7 test tubes (5.0mL), add respectively 9.8 * 10 first -10MolL -1AuNPs, add successively again the melamine of variable concentrations, make it reach respectively certain ultimate density (a, 7 μ gL -1B, 14 μ gL -1C, 21 μ gL -1D, 28 μ gL -1E, 35 μ gL -1F, 42 μ gL -1G, 49 μ gL -1), make potpourri at 25 ℃ of lower reaction 10min, add at last 7.8 * 10 -7MolL -1CdS quantum dot 1mL, measure its fluorescence spectrum.
9. the method for claim 1, wherein said disturbance material is as follows to the interference experiment step of system:
Respectively different interfering materials is joined in the AuNPs-CdS system of the melamine that contains 35 μ g/L, by the described detection method of claim 8, measure fluorescence spectrum; The concentration of each interfering material is respectively Cobastab 1(0.44gL -1), glucose (30gL -1), threonine (143gL -1), K +(143gL -1), Na +(43gL -1), Cl -(141gL -1), NO 3 -(150gL -1), tryptophane (7.5gL -1), glycocoll (7.5gL -1), lysine (14gL -1), histidine (7.5gL -1), vitamin C (1gL -1), Mg 2+(1gL -1), Ca 2+(5.65gL -1), lactose (25gL -1), PO 4 3-(10gL -1).
10. the method for claim 1, the step of the melamine in the wherein said detection milk is as follows:
The melamine of variable concentrations is joined in the milk, make melamine wherein reach respectively certain ultimate density (a, 50 μ gL -1B, 100 μ gL -1C, 150 μ gL -1D, 200 μ gL -1E, 250 μ gL -1F, 300 μ gL -1G, 350 μ gL -1); Then in the centrifuge tube of 10mL, in the milk of 0.5g, add respectively the chloroacetic acid of 3.75mL and the chloroform of 1.25mL, whirlpool concussion 1min, with protein precipitation, and the organism in the dissolved matrix, ultrasonic processing 15min then, the centrifugal 10min precipitation and separation of 12000rmp; The supernatant of 2mL is transferred in another centrifuge tube, used the Na of 1M 2CO 3Adjusting pH is 8.0, solution 10000rmp again centrifugal 10min remove precipitation; Supernatant filters with 0.45 μ m GTTP (polycarbonate leaching film), respectively gets 300 μ L final solutions, by the described detection method of claim 8, joins in the detection system, measures fluorescence spectrum separately.
CN2013100003965A 2013-01-04 2013-01-04 Ultrasensitive fluorescence response method for detecting melamine in milk Pending CN103063643A (en)

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